I usually fill mine either with risotto or just with some other mixed vegies, cream cheese and sweet chilli sauce. MMMM..... :p
I stuff my tomatoes with ground pork meat. The ground meat should be mixed with garlic, onion, salt and pepper (to taste), and seasoning. Mix all these ingredients. Cut the tomatoes in half and put the mixed ingredients. Then cook this in a frying pan. Use an adequate amount of oil.